Field of the Invention
The present invention relates to an internal combustion engine with a multi-link piston-crank mechanism.
Related Art
Patent Document 1 discloses a variable piston stroke type internal combustion engine that includes: a connecting rod connected at an upper end thereof to a piston; an intermediate arm connected at one end thereof to a crankshaft and at the other end thereof to a lower end of the connecting rod; and a control rod having one end connected to the intermediate arm and the other end movably connected as a swing center to a moving mechanism so as to restrict a movement of the intermediate arm and control a stroke amount of the piston.
In Patent Document 1, an oil jet is arranged at a lower end side of a cylinder of the internal combustion engine. This oil jet has a first injection port for injecting engine oil toward the piston and the cylinder and a second injection port for injecting engine oil toward the other-end swing center of the control rod and thus performs the function of cooling and lubricating the piston, the cylinder, the other-end swing-center of the control rod and the moving mechanism.
The so-called multi-link piston-crank mechanism as disclosed in Patent Document 1 is required to maintain an appropriate lubrication state for the purpose of preventing wear and seizing of sliding part on which high load acts.
Although various configurations are proposed for the multi-link piston-crank mechanism, sufficient consideration has not been given as to the lubrication of the sliding part in each of those multi-link piston-crank mechanism configurations. There is still room for improvement in the lubrication of the sliding part in the multi-link piston-crank mechanism.
Patent Document 1: Japanese Laid-Open Patent Publication No. 2003-129817